It was a problem child from the start: radioactive waste has been stored in the Asse II mine in the former salt mine in the Wolfenbüttel district of Lower Saxony for decades. Actually, the aces should only be a temporary solution. A temporary repository, so to speak, until it is clear what should happen to the life-threatening waste. But now the operators are literally running out of time. In a little-noticed parliamentary session, the head of the Federal Company for Final Storage (BGE) announced: The Asse is in danger of drowning. The nightmare of numerous experts and also the residents of Lower Saxony could come true. What is currently happening in the nuclear storage facility? Can the worst still be prevented? Everything important at a glance.

The Asse II shaft is one of three facilities in the former mine near Wolfenbüttel in Lower Saxony. Potash and rock salt was mined there in the early 20th century, but operations stopped in the 1960s for economic reasons. The federal government then bought the mine to store nuclear waste there. Even before it was put into operation, the Lower Saxony Mining Authority warned of possible water intrusion, which, as feared, happened in 1979.

There are 13 chambers in the Asse in which around 126,000 barrels of low to medium radioactive waste are stored. It is unclear, however, how much nuclear waste is actually stored in the Asse. According to official information, the salt dome is said to contain 104 tonnes of uranium, 81 tonnes of thorium and 29 kilograms of plutonium. More than ten years ago, however, it emerged that there were still almost 15,000 unlabelled barrels in the Asse. Contents: unknown.

There is also criticism of the lack of caution during storage: “If the barrels were initially placed on top of and next to each other, they were later simply tipped into the storage chamber,” complains the environmental association BUND.

It has been known since the late 1980s that around 12,000 liters of groundwater from the overburden flow into the mine workings every day. The resulting brine has so far been largely captured. However, some of it entered one of the chambers containing nuclear waste and was therefore radioactively contaminated.

At the beginning of 2024, the disturbing discovery followed: the amount of salt water at the main collection point at a depth of 658 meters is decreasing. Since April, the amount of lye on the 725 meter level below has increased significantly. According to BGE, the liquid has not yet reached the nuclear waste and is not contaminated.

The reasons for this are still largely unclear. However, the ongoing mountain pressure on the pit may have changed the path of the inflowing salt water. In addition, the collection points can become leaky due to constant movement.

For the Greens in the Bundestag, the incident in Lower Saxony is another reason for the end of nuclear power. “The Asse is once again showing what risks the legacy of this high-risk technology poses for future generations,” said Green party leader Britta Haßelmann to the AFP news agency and reiterated: “It is good that the use of nuclear power is now finally over . Also so that more nuclear waste is not generated. Our country is now consistently focusing on the expansion of renewable energies.”

Lower Saxony’s Environment Minister Christian Meyer spoke of a “nuclear disaster in the Asse” and called on the operator to take measures as quickly as possible to prevent the uncontrolled spread of the salt water.

Federal Environment Minister Steffi Lemke (Greens) told the DPA that recovering the nuclear waste was “the safest option at the moment” and “remains our top priority.” “Anything else would have incalculable consequences for the health of the population and the environment of the entire region,” said a statement released after the increased water ingress became known.

The mine was originally intended as a final storage facility. In the 1980s, however, the federal government at the time decided that the Asse could be used for research purposes and that nuclear waste could only be stored there temporarily. The reason: the mine is unstable. In the long term, it cannot be ruled out that not only salt water flows into the pit through cracks in the walls, but radioactive substances are also released. The nuclear waste has to go, which is why the German Bundestag has passed a law according to which the waste must be recovered as quickly as possible. Only then should the mine be shut down.

The BGE experts are still working on solutions for how the radioactive waste can be safely transported away. The garbage is scheduled to be removed in 2033. According to estimates, the preparation for this alone could cost around 4.7 billion euros. The total costs including transport and final storage cannot yet be predicted.

BGE experts are currently trying to find the damaged area. In addition, the entire main collection point at a depth of 658 meters is to be renovated and a new drainage system for the salt water to be collected is to be installed. If the brine continues to flow uncontrollably into the lower levels towards the nuclear waste, the emergency plans could be implemented. These envisage flooding the entire mine.

On May 27, those responsible for the BGE will answer questions from members of parliament during a public meeting of the Committee on Environment, Energy and Climate Protection of the Lower Saxony State Parliament.


Sources: Federal Society for Final Storage, Federal Office for the Safety of Nuclear Waste Management, Nuclear Waste Report, BUND, Asse Leach Situation Report, DPA, AFP